<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    var row = parseInt( prompt('请输入几行') )
    var col = parseInt( prompt('请输入几列') )

    var str = ''
    for(var i = 0; i < row; i++) {  // 行
      for(var j = 0; j < col; j++) {  // 每行有几列
        str += '⭐️'
      }
      str += '\n'
    }

    console.log(str)
  </script>
</body>
</html>